During the wiping operation of a windshield wiper some portions of the blade member deteriorate before other portions. As a result of these deteriorations undesirable streaks are formed on the windshield of the vehicle during subsequent operation of the windshield wiper. In order to eliminate these streaks and also to increase the effective area wiped by the blade member, prior art methods and apparatus have directed their attention to the solution of these problems. For example, U.S. Pat. No. of Perkins et al, 2,821,735 discloses a windshield wiper which is designed and constructed as to affect a relative displacement of the wiper blade to its carrier or actuating arm so that when moved in one direction the wiper blade will travel over a given area of the windshield and when moved in the opposite direction it will travel over a somewhat extended or partially overlapped area to that of the companion wiper stroke. The wiper blade is suspended from the actuating arm so as to automatically cause its end-wise displacement relative thereto. The wiper blade is automatically caused to be relatively displaced by a pair of links pivotally connecting the wiper blade member and the arm member. Stop means limit the longitudinal movement of the arm and wiper blade members longitudinally with respect to each other.
Likewise the U.S. Pat. No. to Kato 3,422,480 discloses a windshield wiper apparatus for use in a vehicle comprising a crank arm connected to a driving shaft and which is adapted to be rotated thereby. A wiper arm is pivotally connected to one end of the crank arm and has a wiper blade fixedly mounted thereon at the other end thereof. An oscillation lever is pivotally connected at one end of the wiper arm at a point between the opposite ends thereof and is also pivotally connected at a point near the other end whereby the blade upon rotation of the crank arm is driven to move in such manner that the ends of the blade describe loops on the surface of the windshield.
Other windshield wiper attachments generally of the type to which this invention relates are disclosed in the U.S. Pat. Nos. of Carey 2,412,319, Lacey, 2,644,187 and Wise 2,809,388.